As an inertial device with which a sensitive carrier makes angular movement, a gyro is a key device used for inertial navigation or guidance. A vibratory gyro based on the Coriolis force theory has all of the necessary merits, becomes more and more important in the field of inertial technology, and has been widely used as a new-generation inertial instrument. Promoted by technology development and market demand, various vibratory gyros have arisen successively. Currently, the most widely used vibratory gyros may be divided in terms of structure into a shell vibratory gyro, a ring vibratory gyro, a disk vibratory gyro and a beam vibratory gyro.
These gyros detect an applied angular rate by precession of vibration forms of a sensitive standing wave using the Coriolis effect. Differences in structure cause their advantages and disadvantages to be obvious. Specifically, as for the ring vibratory gyro, since the design for its supporting structure is complicated and an axial direction of a vibratory standing wave is hard to control so that an error in a direction perpendicular to the axial direction is readily introduced, such structured gyro is low in accuracy and thus is widely used as a MEMS gyro; balance between the supporting structure and a vibrating ring is ensured by virtue of micro mechanical machining, but the ring vibratory gyro has a poor capability to resist against impact. As for the disk vibratory gyro, since its capability to resist against impact is poor and planarity of a disk is hard to guarantee, development thereof encounters a bottleneck and has been turned to a micro mechanical stage in which it approaches the ring vibratory gyro by disk etching. As for the beam vibratory gyro, it mainly has a tuning fork type and a vibrating beam type, is poor in its capability to resist against impact and is low in accuracy, and thus is also widely used as a MEMS gyro. As for the shell vibratory gyro, it is presently the most accurate vibratory gyro, is typically in the forms of a hemispheric resonant gyro and a cylindrical vibratory gyro, and is widely used in respective fields. However, the existing gyros of this kind are poor in their capability to resist against impact, expensive in cost, and complicated to manufacture, thus they cannot meet the requirements for application in the field of high-impact and mid or low-precision angular rate measurement. Though the cylindrical vibratory gyro employs a method of piezoelectric excitation and piezoelectric detection, it has a low quality factor and a poor impact resistant capability due to restrictions caused by its own structure.
Chinese patent granted as No. ZL201010215745.1 and entitled “BELL-SHAPED VIBRATOR TYPE ANGULAR RATE GYRO” provides a bell-shaped vibrator type angular rate gyro which is a vibratory gyro based on the Coriolis force theory. In this patent, a bell-shaped harmonic oscillator made of a molten quartz material is used as a sensitive element, electrostatic excitation and capacitive detection are employed, and excitation electrodes are mounted on an outer cover of a vibrator shell so that difficulty of machining and mounting is increased. This bell-shaped vibrator type angular rate gyro can not bear high overload due to restriction of the material per se, and is higher in cost as compared with the bell-shaped vibrator type angular rate gyro of the present invention. Chinese patent granted as No. ZL201110117526.4 and entitled “METHOD FOR DESIGNING STRUCTURE OF BELL-SHAPED VIBRATOR TYPE ANGULAR RATE GYRO” provides a method for designing the structure of a bell-shaped vibrator type angular rate gyro. In the detailed description of this patent, the vibrator to be used is a bell-shaped vibrator like a round cup which is not subjected to multi curved surface combination and has a low quality factor. All the shell vibratory gyros available at present have a single curved surface structure in which a vibrator wall is a hemispheric or cylindrical structure without a change of curvature. The above bell-shaped vibrator type angular rate gyros adopt the idea of a curved edge to improve the stability of the vibration. However, the concrete curved structure uses natural curves which did not undergo accurate analysis, thereby limiting improvement of the quality factor to a certain extent. With regard to signal processing, the conventional bell-shaped gyros and hemispheric resonant gyros both employ electrostatic excitation and capacitive detection, and vibration forms thereof are subjected to feedback control by using the vibration forms detected by a capacitor, which causes reduction of band width of the entire system.